(Expanding my comment into an answer.)
Provided a question is otherwise on-topic, i.e. relevant to personal finance, then I think that "You ought to check with a [lawyer | accountant]" can often be a useful disclaimer and suggestion on a helpful answer that touches on matters of law or specific accounting rules.
But, I don't think "check with a [lawyer | accountant]" is, by itself, a valid close reason.
In fact, we'd like for lawyers and accountants who know about personal finance matters to come here and answer questions! Stack Exchange sites are for experts including the professionals. We just don't have many accounting and legal professionals here, yet.
On the subject of disclaimers, I'll point out there is already a disclaimer on the Stack Exchange legal page, under Section 5, Warranty disclaimer:
The Services, Content, Network and any Software are provided on an "as is" basis, without warranties of any kind, either express or
implied, including, without limitation, implied warranties of
merchantability, fitness for a particular purpose or
... I'd personally feel better seeing something along those lines in the footer of every page on the site, but, what the heck do I know? IANAL. :-)